About Peter III event...
Ryan suggested:
code:--------------------------------------------------------------------------------#Claims of the House Gottorp
event = {
id = 40131
trigger = {
monarch = 05147
}
random = no
country = RUS
name = "Claims of the House Gottorp"
desc = "As well as being the newly crowned Tzar of Russia, Petr III was also Duke of the house Gottorp. A dysnasty which held claims to parts of Slesvig and Holstein."
style = 4
date = { day = 20 month = january year = 1761 }
action_a = {
name = "These lands will be ours once more."
command = { type = addcore which = 306 }
}--------------------------------------------------------------------------------
I'm not sure if this event rings right bell by historical approach:
Russia was bleeded white by Seven' Years War - according to "Worterbuch zur Deutschen Militar Geschichten" (Russian sources rather vague on this subject with a reason!) Russia to 1762 lost more soldiers then all other participitans of war taken as whole - then while Officers of German origin (Orlov's - for example - whose mother had maiden name - von Ritt, or Suvorov - whose mother was Deutsch as well) supported Ekatherine II the Great claim on throne (these guys were deprived from taking part in this war due to their blood-origin) over-threw Polish-oriented surrounding of deceased Elisabeth Petrovna (maiden name of her mother was Skawronska) - there wasn't slavonic-origin officers led military troops enough for stopping them (& support so-named "Polish" party led by Kanzler Vorontzov). It means - military human resources of Russia was on the brink & it was main reason for hasty peacetalks with a Friedrich by Peter III - not anything else.
Would Peter III or anyone else claim Gottorp supported as fighting Pruusia as non-fighting with Russia Great Britain? I'm afraid not - it would be - sure defeat against combined Prussian land & British naval force. Then...
Then this event can be done, but it need heavy editing. For example:
action_a ={ #Forget about it#
command = { type = relation which = ENG value = 200 }
command = { type = relation which = PRU value = 100 }
command = { type = DIP which = -3 value = 240 }
action_b = {
name = "These lands will be ours once more."
command = { type = addcore which = 306 }
command = { type = revoltrisk which = 36 value = 3 }
command = { type = stability value = -3 }
command = { type = relation which = ENG value = -200 }
command = { type = relation which = PRU value = -100 }
or something similar...

- not sure about it.
In any case we need some tools for improving RUS-ENG & RUS-PRU attitude in around 1761-1762 & worsening RUS-FRA & RUS-POL diplomatic attitude. Giving 306 as shield for Russia is a step in definitely wrong direction.
Just mine 2 Kopecks about it

.
Brgds, Bash.